492 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
is the Synaptula vivipara of (Ersted. It occurs in large numbers in the 
so-called “lakes” at Port Royal, in Jamaica, apparently always inha- 
biting the branches of Acantliopliora thierii , one of the Florideae. 
Breeding probably goes on all the year round, and birth takes place by 
the rupture of the body-wall close to the anus. The ova seem to be 
shed into the body-cavity by the rupture of the epithelium of the gonad. 
The genital duct has no obvious opening to the exterior, but as it is 
usually filled with spermatozoa, there are probably minute openings 
through which these escape. The author believes that cross-fertilisation 
occurs at least usually, the sperms reaching the body-cavity, and thence 
the eggs through tubes which connect the rectum and the body-cavity. 
The animals being social, the water must be tilled with sperms which 
may enter through the anus. Development takes place within the body- 
cavity, and the elliptical larva is without ciliated bands, calcareous 
plates, or larval nervous system. The development of the pentactula 
occurs much as in other species, but there is no cessation of growth at 
this period, and the pentactula is gradually transformed into the adult. 
An important difference from S. digitata is the total absence of radial 
canals even in the cmtiryo. As to the structure of the adult, besides 
the points already mentioned, we note as peculiarities the presence of 
“ eyes ” at the base of the tentacles, and the fact that the stone-canal 
opens both to the exterior and into the body-cavity. The author con- 
siders that his observations support Ludwig’s view that the Synaptidae 
are degenerate pedate Holothurians. 
Experiments with Sea-Urchin Eggs.*' — Prof. J. Loeb finds that 
weak alkaline solutions quicken the development of the eggs of Arbacia. 
The quantity required is very minute, 1J-2 ccm. of a 0*1 normal 
sodium hydrate solution to 100 ccm. of sea-water (about *0006 per cent.) 
Acids have an inhibiting effect. It is suggested that alkalies promote 
the oxidation processes and thus the synthetic processes in the cells, 
and that inequalities in growth may be partly dependent on differences 
in the alkalinity or acidity of different portions of the germinal area. 
Corroboratory experiments were made on the eggs of the Teleost fish 
Fundulus ; the addition of a little hydrochloric acid retarded the develop- 
ment ; the addition of an alkali had hardly any effect. 
Notes on Arctic Echinoderms.t — Herr L. Doderlein describes inter- 
radial brood-chambers above the openings of the ovaries in Pteraster 
hexactis Verrill, and makes various other notes, e.g. on the variability 
of the calcareous plates of the dorsal skeleton of Solaster ( Crossaster ) 
papposus , and on the specific stability of S. syrtensis, &c. 
Reproductive Organs of Echinoderms.j:— Prof. A. Russo maintains 
(1) that in all the groups of Echinoderms the reproductive cells dif- 
ferentiate from peritoneal elements which line the general cavity; (2) 
that the reproductive elements, as in many groups of higher animals, 
originally form cellular cords which by special adaptations afterwards 
acquire their characteristic form ; (3) that the living forms may be 
divided into two groups as regards their gonads, the one including 
* Arch. Entwickmech., vii. (1898) pp. 631-41 (1 pi.). See Zool. Centralbl., vi. 
(1899) p. 380. 
t Zool. Anzeig., xxii. (1899) pp. 337-9. t Tom. cit., pp. 288-92 (3 figs.). 
